Created Data consumption of mobile apps (markdown)

Data-consumption-of-mobile-apps.md

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+This article can be used to store information on the data consumption that can be experienced with the SAP Sailing Analytics Android apps.
+
+## Android apps
+
+### Sail InSight
+
+Energy consumption of the tracking itself is - without any optimization and compression of the messages at the time of writing this - quite low already. Ten hours of tracking mean less than five MB of data volume for the messages themselve, if you choose to send them immediately. If sent in intervalls you can minimize the size of the messages further, since you do not have to sent the devices UUID with every fix. Sending every second message together with the previous one will theoretically equal to around three to four MB of data volume needed for ten hours of tracking.
+
+It is technically possible to compress the sent JSON messages with GZIP. Even if every message is sent individually you can achieve a compression ratio of ~103% which on it's own is not a lot, but at least it does not make it worse. Where it would really come in handy is when several messages are sent together. At a 5 second sending intervall, you can already achieve compression ratios of 300% and more. The challenge with sending GZIP-compressed JSON messages to the server is that this has to be supported by the webserver. Normally only messages sent from the server to the client can contain compressed content. There are ways to enable Apaches to receive compressed content, this definitely could use some testing.
+
+Since the app not only produces traffic when tracking, but also when checking in to a event or reopening that, when loading and sending team photos etc. energy consumption is significantly higher than the previously mentioned values. Since we cannot determine how often users will open and close the app, open the regattas, refresh photos etc. we cannot give good estimations on that even if we knew how much data volume every single one of these actions costs.
+What we can say is, that testing the app extensively over a time of four weeks with booking into events probably more than 100 times and tracking way more than 30 hours caused around 50 to 100 MB of traffic on the testing phones.
+Under normal conditions the traffic for one event should stay well below the former of these numbers.
+
+### Buoy Pinger app
+
+no information yet
+
+### Racecommittee app
+
+no information yet
+
+## iOS apps
+
+### Sail InSight
+
+no information yet